1. Field of the Invention
The present invention relates to an electrode pair structure of a plasma display panel (PDP), and more particularly, to an electrode pair structure of a PDP that includes a pair of metal electrodes, and each metal electrode is composed of a series of hollow, multilateral, and annular metal structures.
2. Description of Related Art
A display device generally falls into two categories, which are the cathode ray tube and the flat panel display. Furthermore, the flat panel display has various types, such as the liquid crystal display (LCD), the plasma display panel (PDP), or the field emission display (FED). Since the PD has many beneficial characteristics such as being thin, having a lightweight design, having large display sizes, giving off no irradiation, and having a wide viewing angle, the PDP has been used widely in the large scale full-color display field.
Referring to FIGS. 1 and 2, FIG. 1 is a schematic diagram of a conventional PDP 10, and FIG. 2 is a cross-sectional view of the PDP 10 along line 2–2′, shown in FIG. 1. As shown in FIG. 1, the conventional PDP 10 mainly includes a front substrate 12, a rear substrate 14 positioned parallel with the front substrate 12, and a discharge gas 16 formed between the front substrate 12 and the rear substrate 14. In addition, the PDP 10 includes at least one electrode pair 18 positioned on a lower, surface of the front substrate 12, a black matrix (BM) layer 20 positioned on the lower surface of the front substrate and outside the electrode pair 18 for increasing the image contrast, a transparent dielectric layer 22 positioned on the electrode pair 18 and the BM layer 20, and a passivation layer 24 positioned on the transparent dielectric layer 22 for preventing ions of the discharge gas 16 from colliding with the transparent dielectric layer 22 and the electrode pair 18, and increasing the life of the PDP 10.
Moreover, the electrode pair 18 is composed of two electrodes 18a and 18b in parallel with each other, and a discharge gap 26 is formed between the two electrodes 18a and 18b. Further, the electrode 18a includes a sustaining electrode 28a and a bus electrode 30a positioned outside the sustaining electrode 28a. Likewise, the electrode 18b includes a sustaining electrode 28b and a bus electrode 30b positioned outside the sustaining electrode 28b. Typically, the sustaining electrodes 28a and 28b both function as transparent electrodes of the PDP 10 and are composed of indium tin oxide (ITO) or stannum dioxide (SnO2). The transparent electrodes are previous to light, but have a large resistance value. The bus electrodes 30a and 30b both function as opaque electrodes of the PDP 10 and are composed of metallic materials, such as chromium/copper/chromium (Cr/Cu/Cr) or silver (Ag). The opaque electrodes are not previous to light, but have excellent electric conductivity for assisting the transparent electrodes to conduct electricity.
In addition, the PDP 10 includes a plurality of address electrodes 32, namely data electrodes, positioned perpendicularly to the sustaining electrodes 28a and 28b and on an upper surface of the rear substrate 14, a white reflective dielectric layer 34 positioned on the upper surface of the rear substrate 14 and covering the address electrodes 32, a plurality of parallel ribs 36 positioned between two adjacent address electrodes 32 and on the white reflective dielectric layer 34, red/green/blue fluorescence layers 38R/38G/38B coated between two adjacent ribs 36 and on the white reflective dielectric layer 34, and two sidewalls of each rib 32, respectively. The white reflective dielectric layer 34 is used to raise reflection of the visible light, increase the brightness of the PDP 10, and planarize the surface of the rear substrate 14. When the discharge gas 16 is excited and dissociated, ultraviolet (UV) ray is generated to irradiate the fluorescence layers 38R/38G/38B to generate red/green/blue beams, respectively.
In the method for forming the transparent electrodes, a physical sputtering process is performed to form a transparent conductive metal layer on the front substrate, and then an etching process is performed to form a desired pattern of the transparent electrodes in the transparent conductive metal layer. However, the shape and the thickness of the transparent electrodes have to be controlled precisely under the demands of the PDP being of large scale and having a high resolution, and the transparent electrodes have disadvantages of the larger resistance value and will reduce the brightness of the PDP. Therefore, a PDP that ignores the transparent electrodes has been disclosed to reduce cost and to increase yield of the PDP.
Referring to FIG. 3, it is a chematic diagram of another conventional PDP 40. The PDP 40 ignores the transparent electrodes of the PDP 10, and only utilizes the opaque electrodes positioned on the surface of the front substrate as the electrode pair of the PDP 40. Also, opaque bus electrodes with fence structures are utilized in the PDP 40 to replace the conventional opaque bus electrodes with slit structures of the FDP 10.
As shown in FIG. 3, the PDP 40 includes at least one fence-shaped metal electrode pair 42 positioned on a lower surface of a front substrate (not shown in FIG. 3), and a plurality of address electrodes 44, which are positioned perpendicularly with respect to the metal electrode pair 42, positioned between the ribs (not shown in FIG. 3) and on an upper surface of a rear substrate (not shown in FIG. 3) of the PDP 40. The metal electrode pair 42 is composed of two fence-shaped metal electrodes 42a and 42b in parallel with each other. Moreover, the metal electrodes 42a and 42b are both composed of three horizontal electrodes 46a and a plurality of vertical electrodes 46b connected to the three horizontal electrodes 46a, respectively. Furthermore, a width H2 of each metal electrode 42a or 42b is substantially equal to a width H1 of each transparent electrode 28a shown in FIG. 2. The vertical electrodes 46b are used to prevent the metal electrodes 42a and 42b from short-circuiting, since the horizontal electrodes 46a are cut off in the manufacturing process for forming the metal electrodes 42a and 46b or by an improper external force pressing the horizontal electrodes 46a. Therefore, the current can flow through the continuous vertical electrodes 46b, not the discontinuous horizontal electrodes 46a, to avoid the above-mentioned problems. In addition, the vertical electrodes 46b can be formed on the front substrate corresponding to the underlying ribs of the rear substrate (not shown in FIG. 3) to prevent affecting the brightness of the PDP 40.
The conventional PDP 40 ignores the transparent electrodes and forms the fence-shaped metal electrodes 42a and 42b on the front substrate directly, so as to decrease the process of forming the transparent electrodes, reduce cost, and lower the complexity of the process. However, the electrode areas of the fence-shaped metal electrodes 42a and 42b are too large, so as to shield the discharge area too much, and cause the display brightness of the PDP to be lowered substantially. Therefore, the fence-shaped metal electrodes 42a and 42b are not suitable for application in mass production of the PDP.
Since the widths of the horizontal electrodes 46a and the vertical electrode 46b of the PDP 40 are very narrow, the horizontal electrodes 46a and the vertical electrode 46b could be cut off easily during the manufacturing process, which leads to the short-circuiting phenomenon. Because of the limitation of the photolitbographic process, when increasing the resolution of the PDP, the fence-shaped metal electrodes with small line width are very difficult to form and control. On the other hand, if the line width of the metal electrode remains wider, the shielding area of the metal electrodes will increase so as to reduce the brightness of the PDP.